1. Field of the Invention
The invention relates to an intra-aortic balloon catheter. More particularly, the invention relates to an improved intra-aortic balloon catheter Y-fitting and sleeve guard.
2. Description of the Prior Art
Intra-aortic balloon (IAB) catheters are used in patients with left heart failure to augment the pumping action of the heart. The catheters, approximately 1 meter long, have an inflatable and deflatable balloon at the distal end. The catheter is typically inserted into the femoral artery and moved up the descending thoracic aorta until the distal tip of the balloon is positioned just below or distal to the left subclavian artery. The proximal end of the catheter remains outside of the patient's body and is connected to a Y-fitting. A passageway for inflating and deflating the balloon extends through the catheter and is connected via the Y-fitting to an external pump. The patient's central aortic pressure is used to time the balloon and the patient's ECG may be used to trigger balloon inflation in synchronous counterpulsation to the patient's heart beat.
Intra-aortic balloon therapy increases coronary artery perfusion, decreases the workload of the left ventricle, and allows healing of the injured myocardium. Ideally, the balloon should be inflating immediately after the aortic valve closes and deflating just prior to the onset of systole. When properly coordinated, the inflation of the balloon raises the patient's diastolic pressure, increasing the oxygen supply to the myocardium; and balloon deflation just prior to the onset of systole lowers the patient's diastolic pressure, reducing myocardial oxygen demand.
Intra-aortic balloon catheters may also have a passageway or lumen which can be used to measure aortic pressure. In this dual lumen construction, the central lumen may also be used to accommodate a guide wire to facilitate placement of the catheter and to infuse fluids, or to do blood sampling.
Typical dual lumen intra-aortic balloon catheters have an outer, flexible, plastic tube, which serves as the inflating and deflating gas passageway, and a central tube therethrough formed of plastic tubing, stainless steel tubing, or wire coil embedded in plastic tubing. A polyurethane compound is used to form the balloon. Other dual lumen intra-aortic balloon catheters have their central tube embedded or affixed to the inner surface of the outer tube.
The proximal end of the IAB catheter is connected to the pump by a connector, generally a Y-fitting. A sleeve is generally disposed about the exposed portion of the catheter to resist contamination of the catheter. Y-fittings presently on the market have a flat distal face which connects to a proximal end of the sleeve.
All IAB catheters have two opposing design considerations. On the one hand, it is desirable to make the outer diameter of the entire catheter as small as possible: to facilitate insertion of the catheter into the aorta, maximizing blood flow past the inserted catheter, and to allow for the use of a smaller sheath to further maximize distal flow. On the other hand, however, it is desirable to make the inner diameter of the outer tube as large as possible because a large gas path area is required to accomplish the rapid inflation and deflation of the balloon. As a result of these opposing design considerations there is a need for a smaller catheter with a larger gas path area.
A decrease in gas path length also would allow for a decrease in the diameter of the catheter. Design work has generally not focused on altering the gas path length because a catheter with minimal insertable length, given patient anatomy, is absolutely necessary to perform IAB therapy. The present invention decreases the gas path length not by decreasing the insertable length of IAB catheter tube but rather by introducing an innovative catheter-to-pump connector having a tapered distal end.
A Y-fitting connector having a tapered distal end allows the protective sleeve to be at least partially, and preferably entirely, disposed about the connector. Moving at least a portion of the sleeve over the connector eliminates the need for at least a portion of the uninserted section of the catheter, and thus, allows for an overall reduction in length of the catheter without altering the insertable length.
While the IAB catheters presently on the market may be suitable for the particular purpose employed, or for general use, they would not be as suitable for the purposes of the present invention as disclosed hereafter.